Comparative host suitability of viable and nonviable codling moth (Lepidoptera: Tortricidae) eggs for parasitism by Trichogramma platneri (Hymenoptera: Trichogrammatidae)

The ability of the egg parasitoid Trichogramma platneri Nagarkatti to develop successfully in viable and nonviable codling moth, Cydia pomonella (L.), and viable obliquebanded leafroller, Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae), was compared. A larger number of viable codling moth eggs were parasitized per Trichogramma female [reared on Angoumois grain moth, Sitotroga cerealla (Olivier) (Lepidoptera: Gelechiidae), eggs], versus all other egg types. More of the viable codling moth (mean = 32.5 eggs per female) and leafroller eggs (mean = 22.2 eggs per female) ana nonviable eggs from the fertile female x sterile male codling moth cross (mean = 21.1 egg per female) were parasitized than were nonviable eggs from either of the sterile female crosses (mean = 6.0 and 8.5 eggs per female). When reared under humid conditions, the mean percentage of total Trichogramma parasitized eggs able to emerge from viable codling moth eggs (mean = 86.5%) was greater than from any of the nonviable codling moth crosses (mean = 66.2-73.2%). The mean number of T. platneri developing per codling moth eggs (1.4-1.7), mean days of parasitization (6-10 d), and percentage females (55.2-58.3) did not vary between egg types. The mean size of the female hind tibia was larger in T. platneri emerging from viable codling moth eggs versus those of females emerging from viable leafroller and nonviable codling moth eggs. Propagation for 1 generation within the obliquebanded leafroller eggs increased the mean number of leafroller eggs parasitized per T. platneri female from 22.2 to 72.0.